A. Field of Invention
The present invention relates to methods of controlling multiple lighting sources such as those powered by driver circuits and voltage splitting methods, which provides alternative failure modes when one or more individual lighting sources fail.
B. Problems in the Art
LED lighting often consists of an array of LEDs comprising a number of LEDs connected in series to form a string of LEDs, and a number of strings of LEDs connected in parallel. The array may be conveniently comprised in a single fixture, such as found in overhead lighting, or may be spread out among two or more fixtures such as found in pathway lighting.
The electro-optic properties of LEDs are such that the LED functions best when current through the LED rather than voltage applied across the LED is controlled. Connecting a large number of LEDs in a series string results in a relatively low amperage and relatively high total voltage drop across the string. This is beneficial for lighting circuits using multiple LEDs. However, this has the disadvantage that a single LED open circuit failure will prevent current from flowing through all other LEDs connected in series, resulting in the elimination of the illumination provided by all remaining functional LEDs in that series string. This severely reduces the illumination produced by the LED array.
Therefore, many opportunities exist for improving the current state of lighting using multiple LEDs or other solid state sources. It is the intention of this invention to solve or improve over such problems and deficiencies in the art.